Frequency multiplication



June 26, 1934. M. G. wAssl-:RMAN 1,964,373

FREQUENCY MULTIPLICATION Filed Feb. 18 1931 INVENToR mmm @zonas msseamu BY j@ /uJ-M/ if?, E, n r1: n ,Hnxmwwummw; s mj i Y .Il vx E s Q lvv 1| w m N w w ATTORNEY Patented June 26, 1934 FREQUENCY MULTIPLICATION Marian George Wasserman, Paris, France, as-

signor to Compagnie Generale de Telegraphie Sans Fil, Paris, France, a corporation of France Application February 18, 1931, Serial No. 516,564

In France February 22, 1930 5 Claims.

It has been suggested in the prior art, particularly in United States application Serial No. 189,206, filed May 6, 1927, United States Patent No. 1,882,119, issued October 11', 1932, to utilize two waves modulated in phase and thereupon superposed in opposition in order to transmit an amplitude-modulated wave. In the same patent there have also been suggested two methods adapted to symmetrically modulate the phases of waves in each of the differential circuits. The modulation frequency was independent of the frequency of the principal or master generator or oscillators, and the source of the modulator energy was independent of the source of the radio frequency modulated energy.

The present invention discloses a novel frequency multiplication method consisting essentially in modulating the phase of a wave flowing through an electric circuit by a frequency being equal to that of this wave. The circuit scheme to be used comprises preferably two circuits fed from one and the same generator, the currents of these circuits being thereupon superposed in Opposition. If the modulation in phase is effected at the same frequency as that of the master oscillator, then the scheme operates like a frequency doubler. The Wave of the master oscillator being proportional to sin wt, the wave of one of the differential circuits will have this shape:

sin (wt-Ms sin wt) Where qs designates a relatively small angle.

By giving the Wave in the other circuit this form:

sin (wt-p sin wt),

and by superposing these waves, if desired, after amplification in opposition or in pushpull there is obtained sin wt cos sin wt) -l-cos wt sin (e sin wt) sin wt cos (zb sin wt +cos wt sin (qb sin wt): 2 cos wt sin 75 sin 'L'UDE 2 p sin wt cos wt=q5 sin 2wt.

The common circuit wherein these Waves are superposed thus constitutes a source of energy having a frequency 21u. This source may be treated entirely just like an original source, that 'is to say, supply energy either directly or only after ampliiication. Hence, it is possible to defrive therefrom a part of the energy for direct needs while utilizing another part of the energy for exciting two differential circuits similar to the circuits excited by the chief source.

(Cl. Z-36) One of the characteristic features of the present invention is the utilization of the same source of energy and the same modulator circuit for insuring phase modulation of all of the waves of multiple frequency successively obtained. Hence, by applying the phase modulation 'at frequency w to the wave having the form 2wt, what is obtained in the differential circuits are waves of this form:

Sin (2wt{-q sin wt) and sin zwi-ps sin wt) which after superposition in opposition result in:

2c cos 2wt sin wt= sin Brut-p sin wt.

Connecting the circuit wherein these waves are superposed to a high-pass filter stopping the frequencies below Sw, there is obtained at the output end of the said filter the frequency Bw, and this output circuit may again be regarded as an original source. By applying modulation at frequency w to this wave, a frequency 4w would be obtained, and so on. Each harmonic or overtone may be derived from the circuit where it is obtained and utilized separately or else in combination with other` harmonics after amplification and shift of phase according to requirements.

The invention will be described in detail hereinafter. In this description reference will be made to the drawing attached hereto, in which:

Figure 1 shows by way of example a frequency multiplier circuit arranged in accordance with the present invention; while,

Figure 2 illustrates in detail a feature of the arrangement of Figure 1.

Referring to the drawing, and in particular to Figure 1, 1 denotes the generator which, on the one hand, supplies directly at 11 the energy of frequency w if energy of fundamental frequency is desired, and, on the other hand, excites two diiierential circuits 2 and 2', and finally furnishes energy to the modulator circuit 15.

The method of phase variation in circuits 2 and 2 consists in inserting in these circuits an element or phase modulator 14 or 14 the impedance of which may be controlled from a distance by electrical means and varies in accordance the instantaneous values of the current received. By way of example, there could be used a variable impedance element of the kind disclosed in Rothes United States application Serial No. 450,111, iiled May 6, 1930, which is similar to French Patent No. 690,417. For other purposes recourse may be had to a saturated iron cored inductance coil of the kind disclosed in United States application Serial No. 189,206,

filed May 6, 1927, which resulted in United States Patent No. 1,882,119, issued October 11, 1932. By varying the impedance of this saturated system including the inductance coil by a method described in detail in said patent and set forth briefly hereinafter, phase modulation of the currents in circuits 2 and 2' may be accomplished. Such a modulator has been shown in Figure 2. The differential or phase shifted currents owing in circuits 2, 14 and 2', 14', and appearing in the secondary inductances of I and I included in said circuits, are controlled as to relative phase displacement by varying differentially the inductive value of I and I. This may be done as shown here by applying controlling or modulating currents from line 15, as shown, by way of 20 and 20 to the opposed windings in the primary circuits of I and I. The controlling wave from 15 is, as shown, preferably superimposed on a direct current component in I and I and the resultant wave, which grows in value in I when it decreases in I, and vice versa, flows in the secondary circuit of I and I', which are included in circuits 2 and 2 respectively. This determines the inductive values of said circuits and in turn the tune of said circuits. At all events the energy necessary for effecting phase modulation is preferably to be furnished from the master generator 1, and the sense of coupling of the modulator circuit 15 with the elements 14 and 14 will be such that the impedance of the element 14 should be very low when that of the element 14 is of maximum amount, and vice versa.

The non-modulated waves in the circuits 2 and 2' are preferably co-phasal. This disposition combined with the utilization of differen- -tial circuits affords the advantage of suppressing the fundamental wave which thus need not be filtered.

The phase-modulated waves, after amplification in amplifier A if desired, reach circuits 3 and 3 in differential coupling relationship (as indicated by the arrows) with the circuit 4 which constitutes the source of energy having frequency 21D. Hence, it is possible to derive in 12 a part of this energy which may be amplified in A1 and shifted in phase in Ph if this is desired. The circuit 4 in turn excites two other differential circuits 5 and 5 similar to circuits 2 and 2. The phase modulation in these circuits is effected by means of the same modulating circuit 15 by the insertion of the elements 16 and 16 similar to 14 and 14'. After an optional amplification by amplifiers A (in order to compensate the previous energy losses) the modulated waves reach circuits 6 and 6 being in differential coupling relationship (as indicated by the arrows) with circuit 7 passed or traversed by the complex wave which, after being filtered in high-pass filter F1 is transformed into a pure wave Bwt in circuit 8, and this wave may partially be used in 13.

This operation may be repeated again in circuits 9, 10, and 9', 10', and as many more times as may be desired, so as to obtain harmonics 4, 5, etc. The circuit furnishing the wave sin nwt is always preceded by a high-pass filter which would be designated by Fil-2 if the schematic drawing hereto attached were to be enlarged and developed.

It is to be understood that it is possible to modify the circuit arrangement in a way so as not to arrive at a definite harmonic by passing through all of the intermediate harmonics. For this purpose it would suffice to utilize for the phase modulation of certain intermediate circuits a harmonic frequency priorly obtained instead of the frequency of the master oscillator. It would also be feasible to employ for modulation in the successive circuits the frequencies previously obtained, and this could be done in any desired order. It would also be possible to insure a well defined range of harmonics, and these need not necessarily be sequential.

The uses and applications of this circuit arrangement are numerous and depend upon the frequency of the generator or oscillator 1. In case of radio frequency the arrangement could be usefully employed in quartz equipped oscillation generators insuring a high efciency of operation in the multiplier, for the phase-modulation is effected with little power, while the amplier arrangement is constantly being passed by a practically constant-amplitude wave. By way of an example of another application it is possible to superpose all frequencies that have been obtained in one and the same circuit thus resulting in a wave of desired shape. If the frequency of generator 1 is audible, this wave will result in a sound and the circuit scheme could be used in electrical musical instruments. In this case the same instrument could be regulated so as to imitate various ordinary muscial instruments, particularly by a change of timbre. This change could be insured by acting upon the amplifiers A1.

I claim:

l. A frequency multiplier comprising a source of alternating current, a pair of differential circuits fed from said source, each circuit containing an element whose reactance responds to the instantaneous values of the current flowing therethrough, means for varying the reactance of said elements in opposition and at the frequency of the current of said source, whereby the currents in said differential circuits ai'e shifted in phase, and means for combining in opposition the phase shifted currents.

2. A frequency multiplier comprising a source of alternating current, a pair of differential circuits fed with energy from the soiuce, each of said circuits containing an element whose reactance varies in accordance with the instantaneous values of currents flowing therefrom, means coupling the reactances with the source of the current for varying their values in opposition at the frequency of the current of said source, and means for combining in opposition the currents within said differential circuits.

3. A frequency multiplier comprising a source of alternating current, a pair of differential circuits fed with alternating current of the frequency of said source, differentially connected u phase modulating means energized by alternating -135 current of the frequency of said source and coupled to said differential circuits to vary the phases of the currents in said differential circuits at the frequency of said source, and means for superimposing in opposition the phase modulated t MO currents.

4. The method of frequency multiplying electrical oscillations which consists in generating high frequency oscillating electrical wave en- M5 ergy, dividing the generated energy into three portions, modulating the phases of the oscillations in the energy of two portions oppositely by means of the oscillations in the energy of the third portion. and superimposing or addingthel0 frequency of the original wave, separating said resultant into two like portions, modulating the phase of one portion at the frequency of the original wave modulating the phase of the othexl portion at the frequency of the original wave, and recombining said portions in opposition to obtain a resultant, the frequency of which is triple the original frequency.

MARIAN GEORGE WASSERMAN. 

